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AGS vs GIA

AEM27

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I saw some threads on this and was surprised to see that AGS may be better. I'm curious because the jewelers tells me GIA is better so I didn't even look at AGS.
 

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flyingpig

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Neither is better than the other. Many prefer AGS stones because AGS's cut grading is stricter in general. The AGS Platinum also provides the computer generated ASET and their number rounding rules make more sense than GIA's.

I have seen trade members here openly criticizing both AGS GIA. Both labs have limitations.

A jeweler who carries GIA stones will tell you GIA is better.
A jeweler who has partnership with AGS will tell you AGS is better.
A jeweler who carries ungraded stones will tell you diamond reports are meaningless.

Most B&M jewelers will say GIA better because there aren't many AGS stones out there and most jewelers don't have access to them. Whoever says GIA or AGS stone is better than the other is just promoting the products she/he carries.
 
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doberman

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Superideal diamonds come with an AGS report because AGS grades for light performance while GIA does not. It's not really a question of one being better than the other, but AGS is more in-depth than GIA and its cut parameters are more stringent.
 

AEM27

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interesting, just looking on the interenet it always seemed AGS was a bit cheaper for the same specs so sort of bought what I was told, that GIA was better. Is there a reason AGS seems cheaper for the same specs?
 

diamondseeker2006

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AGS ideal cut stones generally are listed at higher prices. Are you sure you aren't confusing another grading lab like EGL? There are great cut stones graded by both labs. It helps to buy from a place that will provide ASET images to show light return. GIA is sometimes stricter with color grading and some say AGS is slightly stricter on clarity grading. The bottom line is that every stone much be evaluated individually and not by which of the two labs graded it. That said, the top cuts, which we call superideal cuts, are often graded by AGS since AGS is more specific in its cut grading.
 

sledge

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Both are trusted labs and IMO the only lab reports to consider when buying. I will take AGS over GIA all day because I value cut above all else and AGS is the only lab that can objectively determine a true cut grade by using advanced 3d scans that GIA doesn't yet have. Also I like the fact AGS is more precise and doesn't do funky rounding of their proportion values.

In short I think AGS is a more accurate report for cut quality because of these measures. Some believe GIA is more strict on color grading although all color grading at both labs is done by humans and consequently somewhat subjective in nature as such.

GIA has more labs across the globe and consequently more well known. Being more popular sometimes makes people think they are better. Kind of reminds me of Apple vs PC in that regards. PC owns the majority of the market but mainly because Apple lost the advertising/popularity contest years ago, not because they are superior.
 

marcy

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I suggest comparing some side by side and see which one your prefer. In my limited observations comparing AGS0 and GIAXXX side by side; I have always preferred the AGS0 diamonds. They appear to have more fire and scintillation. The first time I compared them I didn't have a clue who AGS and GIA were; but both my husband and I picked the AGS diamonds as the diamonds we liked the best.
 

sledge

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I suggest comparing some side by side and see which one your prefer. In my limited observations comparing AGS0 and GIAXXX side by side; I have always preferred the AGS0 diamonds. They appear to have more fire and scintillation. The first time I compared them I didn't have a clue who AGS and GIA were; but both my husband and I picked the AGS diamonds as the diamonds we liked the best.
I'm not sure the specs on the specific GIA XXX stone you compared, but generally speaking GIA has widened their criteria so much that XXX has little significance. Instead, for those shopping GIA stones it is necessary to be critical in the rejection process and target stones within these ideal parameters:
  • 54-57 table
  • 60-62.4 depth (prefer max 62)
  • 34-35 crown (maybe 35.5 with 40.6 pavilion)
  • 40.6-40.9 pavilion (maybe 41 with 34 crown)
  • 75-80 lower girdle facets
This doesnt guarantee awesomeness, but will eliminate the bulk of XXX stones and get you closer to a comparable AGS000 stone. Next you'd want to request idealscope, ASET and H&A images to confirm anticipated light performance and symmetry. The problem is most retailers pushing XXX stones won't readily have those images available forcing the buyer to take blind risk and order the stone for examination with their own eyes and own scopes and then navigate through the return process if things aren't as expected or anticipated.
 

MollyMalone

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GIA is ubiquitous. E.g., as of tonight, there are 1401 round diamonds listed in the PriceScope Diamond Search database that are between .90 ct and 1.05 cts, G - I in color, VS1 - SI1 in clarity, and have an "excellent" HCA score. Only 46 -- just slightly more than 3% -- of those have AGS reports instead of GIA reports.

Although they did have ASET scopes and some other useful aids/tools, none of the 3 jewelers in my Midwestern hometown who are members of AGS actually had any AGS-graded diamonds for sale last summer when curiosity propelled me into researching this while visiting family (and it was a good excuse for me to visit these places!) GIA stones are what make up their loose diamond inventory at hand. One commented that he'd had a customer bring in a Triple 0 AGS stone as a trade-in & he'd sent it off to GIA to get that lab's piece of paper. As he explained, "AGS just doesn't have name recognition with our customers." He also commented that he thinks AGS does not do a very good job of supporting retail members like himself, and their customers, in this regard. "But maybe," he mused, "the lab, at current staffing levels, couldn't handle much of an increase in business anyway." ** Even here in NYC, AGS-graded diamonds are, in my experience, tough to come by.

** I neglected to ask how AGS lab fees compare to those of GIA & what the AGS turn-around time has typically been. That information isn't posted on the AGS web site for public consumption; unlike GIA, we consumers cannot submit stones directly to the AGS lab -- you have to go through an AGS member jeweler.
 

sledge

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You made an interesting comment @MollyMalone. How exactly did this retailer feel "supported" by GIA?

IMO, as a consumer we do not want any independent 3rd party test lab to support a retailer unless it's fast, accurate and low cost test reports.

Labs and retailers need to understand each other but not be intertwined.

As far as the GIA bias, I think the fact you can sell 97% of market availability is the reason they are pushed. Also with GIA XXX criteria so loose you can dupe less savvy buyers into buying a XXX stone based merely on the fact it's XXX instead of having truly ideal proportions and the best cut.

So XXX certification provides lot of fish you can advertise as high trusted quality, whereas AGS is truly the real deal yet has fewer fish and then because they are strict on cut quality reduces their small market share to an even smaller market share.

I think I read truly ideal cut stones comprise about 1-2% of the market availability.

I hate to quote statistics as the opening line of my statistics class professor still rings in my head each time, "99% of statistics is BS".
 

MollyMalone

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You made an interesting comment @MollyMalone. How exactly did this retailer feel "supported" by GIA?
IMO, as a consumer we do not want any independent 3rd party test lab to support a retailer unless it's fast, accurate and low cost test reports.
Labs and retailers need to understand each other but not be intertwined.
His comment about how he thinks AGS could do a better job of supporting retailers and customers followed immediately on the heels of his observation that AGS does not have "name recognition":
* * * One commented that he'd had a customer bring in a Triple 0 AGS stone as a trade-in & he'd sent it off to GIA to get that lab's piece of paper. As he explained, "AGS just doesn't have name recognition with our customers." He also commented that he thinks AGS does not do a very good job of supporting retail members like himself, and their customers, in this regard. * * *
What he meant was that AGS does little consumer-oriented "selling". (Odds are that AGS reports with evaluation of cut performance weren't on your radar screen at the outset of your e-ring shopping.) He said there's been a dearth of freshly minted, ready-made marketing materials that a retail jeweler can offer to prospective purchasers re the value of an AGS lab report. What little media advertising AGS has done is generic, of the "visit your local AGS jeweler" ilk:
https://cdn.ymaws.com/www.americangemsociety.org/resource/resmgr/images/About/Female-Ad-.jpg
https://cdn.ymaws.com/www.americangemsociety.org/resource/resmgr/images/About/Male-Ad.jpg
And I agree with him that the AGS web site -- should an unknowing consumer somehow find their way there -- doesn't do a good job of drawing casual viewers in and easily/quickly offering a compelling presentation re "why an AGSL report vs. GIA." Only My Diamond®, introduced last year a couple of weeks before my visit with this metalsmith-retail jeweler-owner, has some nice features to tout and show to customers
https://www.americangemsociety.org/page/onlymydiamondserv
-- but it is an add-on to a Diamond Quality Document & carries an additional charge.

He had two rings showcased which he himself had fabricated using AGS "super ideals" as the center stone; a few other of his GIA-"certed" diamonds would qualify as super ideal, so it's not as if he's indifferent to cut. (As a colored gem enthusiast, I appreciated the fact that he had AGL reports for his higher priced colored gem pieces -- and I also had fun playing with his $500 ASET® :)) )
 

MollyMalone

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I also think AGS is stricter on color grades
Doesn't seem we've seen an anecdotal consensus here on PS about that. E.g.,
https://www.pricescope.com/community/threads/sounds-like-operation-upgrade-is-about-to-commence.242599/page-5#post-4388371

ETA: found what I thought I remembered seeing on WF's website:
GIA Vs AGS - Color And Clarity Grading
As mentioned, AGSL uses essentially the same methodology as GIA for color and clarity grading, and has established practices to maintain consistency with GIA standards. For instance, both labs use master color sets for grading diamond color. The master sets used by the AGSL are graded by GIA and assembled according to the strict standards GIA has established for their use.
Because color and clarity aspects of diamond quality involve some degree of subjectivity and are ultimately graded by humans, conjecture is often heard that one lab grades more leniently on one or the other aspect than the other lab. The fact is that all major labs recognize an inherent one-grade acceptable deviation.... There have been and always will be cases where diamonds submitted to both labs result in different grades. And those differences go in both directions. No study has been done to effectively demonstrate that one lab is consistently more or less strict on either color or clarity than the other.
https://www.whiteflash.com/ags-vs-gia/

I'll also add that, because color grading is done by humans & involves an assessment along a narrow continuum, it's even possible for the same person at a lab to assign a different color grade to the same stone on two different occasions. Especially if the stone is on either the "high" or "low" end of a particular color grade.
 
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whitewave

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I won’t be able to search today, but I recall several trade discussions and anecdotes about it.
 

ChristineRose

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Very few diamonds are sent to AGS unless the cutter expects the stone to earn the coveted AGS 000. Only the very best cut stones earn a 000. Most AGS 000 are also GIA XXX, but few GIA XXX are also AGS 000. Because of this you can always expect AGS stones to be more expensive. If a GIA XXX was also an AGS 000, it would have been sent to AGS to get the 000.

Other than the different approach to cut grading, they are pretty much the same from a consumer's POV. I am not sure what they meant, but GIA could be called "better" in the sense that they have a much wider selection of stones, including all the slightly less than 000 stones. In practice you may not be able to see a difference, and you can save money.
 

oldminer

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If a GIA graded diamond happened to meet all the cut parameters of AGS 000 it would still simply grade GIA XXX. Savvy folks search, mostly in vain, for such diamonds in hope of obtaining a diamond with very fine cutting and the potential for very fine light behavior without any added premium price.

Consumers should keep in mind that any lab hoping to take any business away from GIA cannot grade color and clarity more conservatively than GIA grades. To do so, would severely impact their chances of finding clients for their lab. They can hope to grade the same as GIA if they have the best motivations and they must compete with labs that grade a little bit softer than GIA at the same time.

AGSL took the most difficult path by making a good effort to grade color and clarity pretty much like the GIA does while setting even a higher standard for cut grading. The end result is that we find a only small percentage of diamonds suitable for AGSL grading. The statistic bear this out and it surely has had a negative impact for the AGSL in terms of growth. For those who have interest in the finest cut quality, the path of using only AGSL reports is clearly a great choice. For those who want a larger selection without a premium cost, then GIA is the most common alternative. Using an Ideal-Scope or ASET scope with GIA grade diamonds makes sense in this compromise as the GIA range of their top cut category is somewhat overly broad.
 

ChristineRose

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John Pollack had an interesting post about the color grading a while ago. So far as I know, no one has ever sent a bunch of stones to both AGS and GIA and compared the color grade. To do it right you'd need at least 40 stones, possibly more.

John Pollack's post suggested that AGS is unusual and special, so that when someone sees an AGS stone that has slipped a little, they note it, but when they see a similar slip in the GIA grade they just acknowledge that grades can be one grade off without being considered incorrect. They might send the stone back for regrading and hope the color slips up instead of down.

From what we know about similar tests of subjective judgement (not necessarily involving diamonds but similar impressions that A and B are different) human bias comes into play so often that I would place exactly zero stock in anecdotes without a controlled study.
 

John Pollard

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Who is this John Pollack you speak of? :sun:

John Pollack had an interesting post about the color grading a while ago. So far as I know, no one has ever sent a bunch of stones to both AGS and GIA and compared the color grade. To do it right you'd need at least 40 stones, possibly more.
We send hundreds of stones through GIA each year, serving Far East clients in markets where AGS is unknown. Logically there is crossover, where some diamonds initially passing through one lab may be called-for elsewhere and pass through the other.

This isn't a controlled study, but as intimately acquainted as we are with each diamond I'd submit that our authority regarding our product is more consistent than any outside organization could be. I'd add that our chief gemologist Lieve Peeters is the sole judicial diamond expert for the Belgian Federal police and diamond consultant to Scotland Yard, so we have high confidence in our own preliminary grading.

From our position all labs make mistakes. We recheck grades at any lab, both up and down, based on our authority. For anyone wondering "recheck" is, this post describes the submission and reporting process between the labs and those of us producing diamonds.

https://www.pricescope.com/community/threads/7-4mm-cbi-or-7-68mm-gia-ideal.236887/#post-4273790

The relevant info: GIA grades around 40,000 diamonds per week across nine locations. In worst moments they're off from our assessments by up to 2 grades in both directions. AGSL has only one location and is typically tighter, but tends to swing to one side or the other in specific categories for a while, followed by an internal correction toward center. Whatever the lab, we recheck both ways - up and down - as a matter of brand-protection. Why? Because our retailers cannot order an F from us, have it arrive and be identified as a G, or we'd be sunk. So we're rather sensitive about getting the 'right' grade. And for us, Lieve is always 'right.'

John Pollack's post suggested that AGS is unusual and special, so that when someone sees an AGS stone that has slipped a little, they note it, but when they see a similar slip in the GIA grade they just acknowledge that grades can be one grade off without being considered incorrect. They might send the stone back for regrading and hope the color slips up instead of down.
If memory serves, you may be referencing this post @ChristineRose? It follows the information provided above.

https://www.pricescope.com/community/threads/2-69ct-g-vvs2-worries-feather-natural-ags-color-clarity.203189/#post-3698017
 

ChristineRose

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Who is this John Pollack you speak of? :sun:


We send hundreds of stones through GIA each year, serving Far East clients in markets where AGS is unknown. Logically there is crossover, where some diamonds initially passing through one lab may be called-for elsewhere and pass through the other.

This isn't a controlled study, but as intimately acquainted as we are with each diamond I'd submit that our authority regarding our product is more consistent than any outside organization could be. I'd add that our chief gemologist Lieve Peeters is the sole judicial diamond expert for the Belgian Federal police and diamond consultant to Scotland Yard, so we have high confidence in our own preliminary grading.

From our position all labs make mistakes. We recheck grades at any lab, both up and down, based on our authority. For anyone wondering "recheck" is, this post describes the submission and reporting process between the labs and those of us producing diamonds.

https://www.pricescope.com/community/threads/7-4mm-cbi-or-7-68mm-gia-ideal.236887/#post-4273790

The relevant info: GIA grades around 40,000 diamonds per week across nine locations. In worst moments they're off from our assessments by up to 2 grades in both directions. AGSL has only one location and is typically tighter, but tends to swing to one side or the other in specific categories for a while, followed by an internal correction toward center. Whatever the lab, we recheck both ways - up and down - as a matter of brand-protection. Why? Because our retailers cannot order an F from us, have it arrive and be identified as a G, or we'd be sunk. So we're rather sensitive about getting the 'right' grade. And for us, Lieve is always 'right.'


If memory serves, you may be referencing this post @ChristineRose? It follows the information provided above.

https://www.pricescope.com/community/threads/2-69ct-g-vvs2-worries-feather-natural-ags-color-clarity.203189/#post-3698017
Why, yes this would be it!

Thank you Mr. Pollard.
 

JLW05

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Just wanted to share my experience for whatever it is worth as AGS vs GIA comes up on this forum from time to time. It has been my observation that jewelers who are dismissive of AGS and praise GIA, primarily carry GIA stones and vica versa. I have WF studs and needed a new appraisal in order to renew my insurance policy. When I purchased the stones, I did not have them independently appraised so I was a bit apprehensive and curious about the color grade as some posters have opined that AGS is a bit softer in color than AGS. I did not give the appraiser any info about color or clarity. With my permission, he looked up the AGS reports, but not before he gave his own opinion on color and clarity. He graded each diamond as H (as per the AGS reports) and felt that one of the earrings was a borderline VS1 and the other a VS2. Both diamonds were purchased as VS2 in clarity. The appraiser stated that he felt the diamonds were strictly graded by AGS and that in his opinion AGS is a bit more consistent than GIA.
 

Gussie

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Wonder why more stones don't have dual certificates. Anyone know?
 

sledge

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Cost and hassle.

Why have two if the majority of your buyers want a GIA or AGS cert. Also many GIA 3x stones get top tier excellent grade but wouldn't make top notch ideal grade from AGS. Although any AGS ideal 0 should easily make GIA excellent.
 

Gussie

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Cost and hassle.

Why have two if the majority of your buyers want a GIA or AGS cert. Also many GIA 3x stones get top tier excellent grade but wouldn't make top notch ideal grade from AGS. Although any AGS ideal 0 should easily make GIA excellent.
In some cases it makes sense. I think I would prefer both though. The cost is relatively low. AGS satisfies the small number of people who value cut, but GIA is more well known.
 

sledge

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In some cases it makes sense. I think I would prefer both though. The cost is relatively low. AGS satisfies the small number of people who value cut, but GIA is more well known.
I'm sure some of the vendors would accommodate this special request if the customer was willing to pay for the additional lab, shipping and handling fees.

To see dual certification as a "standard" seems unlikely. The purpose of the cert is to provide a trusted and independent 3rd party opinion concerning the quality of the diamond. In a sense the certification provides confidence that the product you are buying is of a certain quality.

That said, more educated buyers realize there can be a 1 +/- grade variance in color and clarity grading between labs due to the subjective nature of the test. The average buyer likely does not know this.

So imagine situations where grading is not identical between the labs. It will erode general consumer confidence. Also it can have a direct impact on pricing. If one lab gives a color grade D and another E, which price does the customer pay?

The consumer will want to pay the least money. The vendor will want to charge the most money. Both are fair and logical conclusions.

It seems logical an agreement of sorts on pricing needs reached prior to getting a second opinion. But I think it's obvious how this element creates a potential problem .

Vendors may push up pricing to ensure they receive anticipated profits because of grading adjustments. Buyers would love a price drop but be turned off by a price increase.

So yes, I understand and agree some situations dictate a second cert; however, I think there are some valid reasons (besides cost) that currently make it difficult for it to be a mainstream and accepted common practice. To make a shift you have to educate consumers why it's good and some customers will undoubtedly say I like AGS or GIA and do not need dual certs and don't want to pay the premium.
 

Karl_K

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Wonder why more stones don't have dual certificates. Anyone know?
A vendor here many years ago tried duel reports, after spending a bunch of money it was given up.
To many one grade differences both up and down one to the other.
No real pattern either other than AGSL being harsher at vs2/si1/si2 breaks fairly often.
That and the period where AGSL was grading legit si2 as i1 diamonds is where the AGSL reputation for being harsher on clarity came from.
None of what they found is really relevant to today because there have been a ton of changes at both labs.
These days it seems the opinion is that GIA has a hard time staying within one grade of itself with all the different locations.
My opinion is sadly all color and clarity grading has a resolution of +/- 1 grade.
 

Texas Leaguer

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An important thing to understand in the discussion of AGS vs GIA is that they are sister organizations. They were both founded by the same people for somewhat different purposes. GIA for education, AGS as an organization for ethical retailers using best practices. The two organizations continue to collaborate in many significant ways. An AGS member must have an AGS Certified gemologist on staff and part of that requirement is that they have a GG from GIA. GIA courses are taught several times a year on the AGS campus.

AGS Laboratories is a relatively recent development, combining GIA grading of color and clarity and a state-of-the-art light performance based cut grading. Color grading at AGS is done with GIA vetted master sets.

There is a very high degree of alignment between the two labs regarding color and clarity grading. As @Karl_K points out, because color and clarity are ultimately human grading calls, and because color and clarity grades are small ranges on a continuum, there is a logical and accepted range of +/- 1 grade.

Because GIA is so well known globally there is a tendency in the market to consider GIA the 'true' grade even though it is by definition an educated opinion. Ironically, as @Karl_K also points out, GIA has grown so big that inconsistencies in grading have been an issue. All grading at AGSL is done under one roof and by a core team that has been together for years.

We deal in both AGS and GIA graded diamonds and can attest to the high degree of alignment. We occassionally see the 1 grade variance and it goes in both directions without any clear pattern. As @sledge explains, the idea of dual certs is not only expensive but can introduce uncertainty to shoppers who may not be thoroughly acquainted with laboratory grading. We do accomodate customer requests when practical to send diamonds to GIA for an additional report if the customer is willing to pay for the service, and two way shipping and insurance, and providing they understand the potential variance.
 
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Karl_K

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My opinion is sadly all color and clarity grading has a resolution of +/- 1 grade.
That should have said: My opinion is sadly all color and clarity grading has a resolution of +/- 1 grade at best.
It certainly can be worse than that.
 
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